On the Study of Reconfigurable Intelligent Surfaces in the Near-Field Region

As reconfigurable intelligent surface (RIS) is expected to be implemented with a large aperture in terms of wavelengths, using RIS perform near-field rather than conventional far-field communications might gain some benefits. The electric fields the region from focusing and RISs are simulated compared assess validate Two metrics benefit distance defined characterize region. cumulative distribution function (CDF) related calculated describe benefits area interest where total scan patterns plotted. For demonstration, distance, gain, CDFs presented for assigned focal distances 80 300 mm. It concluded that critical factor affecting CDF directly. effects size phase quantization elements on also discussed. Moreover, maximum certain derived specified. Finally, three prototypes (e.g., RIS, 500 1500 mm) at 26 GHz measured compared, gains experimentally observed.